Investigating the interplay between lipid oxidation and digestion of Antarctic krill oil: focusing on the influence of emulsification capacity

The impact of lipid oxidation on the digestive efficiency of Antarctic krill oil (AKO) was explored, with a focus on the relationship between emulsification efficiency and digestive efficiency. AKO samples underwent oxidation were assessed using a simulated gastrointestinal model. Lipid oxidation was found to significantly reduce emulsification efficiency, as evidenced by a lower density of emulsified lipid droplets in oxidized AKO compared to fresh AKO during simulated intestinal digestion, as observed via optical microscopy and cryo-scanning electron microscopy. The total lipid emulsification efficiency was higher in fresh AKO than in oxidized AKO. Additionally, the release of free fatty acids was lower in oxidized AKO ((14.06 ± 0.42) mmol/L digestive juice) compared to fresh AKO ((17.44 ± 0.68) mmol/L digestive juice) at the end of simulated gastrointestinal digestion. These results suggest that lipid oxidation impairs its emulsification during the process of gastrointestinal digestion by producing less quantity but larger size of lipid droplets, which limit enzymatic access and subsequent absorption during digestion. This underscores the critical role of lipid oxidation level in determining the bioavailability of AKO and highlights the necessity for optimized handling and storage practices to preserve its nutritional integrity in dietary supplements.